COMPARISON OF SPEED OF ONSET OF ANALGESIC EFFECT OF DIAMORPHINE AND MORPHINE

In a random, double-blind crossover trial using an ischaemiclimb pain model we have assessed the speed of onset of analgesiaafter an i.v. bolus of equipotent doses of diamorphine and morphinein 12 healthy male volunteers. Pain and its subsequent reliefwere assessed by means of a visual analogue scale. Two of thesubjects found diamorphine acted quicker than morphine, onefound no difference and nine found that morphine was quickerthan diamorphine. The mean time to diamorphine effect was 53%greater than for morphine (P < 0.005, Wilcoxon rank sum test).These findings suggest that, for rapid relief of pain, morphineis more suitable than diamorphine.